Bromption Assistance

Discussion in 'Folding Bikes' started by Reuvy, 22 Jun 2017.

  1. Reuvy

    Reuvy New Member


    I proudly own a Brompton 6L which is approximately 5 years old. About six months ago I replace some parts on the Brompton my seatpost was a slightly bent and I needed a new black clip to lock the seatpost and other things.

    Very recently a very professional Brompton mechanic replace the bushings in the rear part of the frame that that falls under it was wobbling a bit. The bicycle now rides smooth. He also received the black ring that sits within the seat tube.

    I am a touch over 6 feet tall and a standard seatpost works for me. But I believe I might be one or two kilos above the weight maximum that Brompton recommends. And very often the seatpost slides down a bit while riding. There is a little bolt on the side of the seatpost I sometimes try to tighten it enough to be able to close the black clamp. But when that both is too tight the seatpost doesn't slide down so easily.

    Mike you have a recommendation to prevent my seatpost from sliding down while riding thank you
  2. Pale Rider

    Pale Rider Guru

    Carbon assembly paste - grease with little granules - helps grip and lubrication.

    The snag with a Brommie is the full length of the post will become smeared with the stuff when dropping and raising the post for the fold.
  3. Fab Foodie

    Fab Foodie hanging-on in quiet desperation ...

    Remove post and clean and degrease the post and seat tube.
    It happens occasionally.
  4. reppans

    reppans Active Member

    Yeah, it's your hand oils on the post - as mentioned degrease length of post and plastic bushing inside the seat tube (I use alcohol). I also don't touch the post anymore - makes it a 2-handed fold-rear-wheel operation, but for me, better than sliding and degreasing.
    CopperBrompton likes this.
  5. 12boy

    12boy Senior Member

    Casper WY USA
    If these strategies don't work, get a 31.8 mm seatpost clamp from the LBS, and remove the little lip on one side. Then remove the saddle and slide the clamp down to where it sits above the seat post frame. Tighten it up a bit and it will prevent the post sliding down. Not as aesthetically pleasing, of course, as having the Brompton one functioning perfectly but it will get her done while you sort out the other. BTW, after replacing the plastic sleeve which is glued within the seatpost I learned the guys who sold it to me ream them out once installed because the original glue on the first sleeve is to remove completely and that makes the seatpost not slide as it should and not clamp evenly and hence slip.
  6. Schwinnsta

    Schwinnsta Regular

    Someone like Bikegang ought to make and market a clip like you describe. I made one and it works.
  7. 12boy

    12boy Senior Member

    Casper WY USA
    At our backfill people leave unwanted bikes free for the taking. Once in a while I will find one worth rebuilding to give away to someone who needs a bike, but I also scavenge parts and have acquired a bunch of QRs and other bits worth keeping when the donor bike is not salvageable. A few minutes with a file and a seatpost QR clamp is good to go. I do need to redo my seatpost sleeve because if I tighten the stock Brompton seat post clamp enough so it doesn't creak, the latch for the suspension block doesn't work properly.
  8. chriscross1966

    chriscross1966 Senior Member

    That would indicate your seatpost sleeve is worn out, exact same thing happened to mine.
  9. e-rider

    e-rider crappy member

    South West
    When i first got my brompton the post slipped but now its fine. What you need to do is: 1. Clean and degrease the post. 2. Tighten bolt up but not so tight that the lever no longer works or the post wont move freely. 3. Wait for the post to get old and scratched as this increases friction - some people light rub with sandpaper but I couldnt do that to a shiny seatpost!
  10. Kell

    Kell Senior Member

    This worked for me...
  11. ryanme

    ryanme Member


    - This is totally unnecessary! - keep the post clean, check it for wear.

    The seat sleeve is a nylon sleeve glued into the frame to stop the frame damage. if you fold your bike daily, 5 days a week for work, thats over 2000 times a year .... this piece of nylon wears and needs replacing.

    Users often find the post slips, or the clamp doesnt go as tight - you can nip this up slightly with a 10mm spanner but get the sleeve changed every year if used 5 days a week!
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